Implanted infusion pumps deliver therapeutic drugs to a patient according to a computer program executed by a processor that is programmed with drug dosing parameters. A microprocessor controls a small, positive displacement pump according to programming instructions delivered to the microprocessor through an RF programming link so as to permit the implantable pump to be remotely programmed and operated. In the course of executing its program, the processor controls a mechanical pump according to programmed dosage parameters.
A problem with prior art drug infusion pumps are that they run open-loop, i.e. there is no feedback mechanism controlling drug dosing. Moreover when used for treating many disorders, implantable infusion pumps need to permit the patient to self-administer a bolus of medication on demand. For example, many diabetics need to administer a bolus of insulin either just prior to or just after a meal. The changing of drug infusion rates is important as the insulin requirements of diabetic patients' change during the course of a day. Therefore, it is important that any drug treatment system be able to accommodate a predetermined constant delivery rate as well as any adjustments that may be required during the course of a day. However, this frequent changing of dosage rates can lead to potential underdosing or overdosing situations.
While prior art implantable and programmable infusion pumps permit a patient to administer additional drug dosages on demand, these prior art devices do not adequately control the amount of patient-administered dosages increasing the likelihood that a patient may overdose or underdose himself, adversely affecting the patient's physician-prescribed therapy.
A remotely programmable and implantable tissue stimulator is disclosed in U.S. Pat. No. 5,443,486 to Hrdicka et al., for a “Method and Apparatus to Limit Control of Perimeters of Electrical Tissue Stimulators.” While the '486 Patent discloses a remotely programmable tissue stimulator and permits the patient to control the administration of tissue stimuli, the device disclosed in the '486 patent does not provide for programmable drug infusion therapy. Nor does the '486 provide for software-based drug infusion limits.
Programmable infusion limits in implantable infusion pumps might lessen the likelihood that a patient will overdose or underdose himself. Moreover, a software-defined limit might also lessen the likelihood that certain drug regimens will be used improperly—even by health-care providers. By using a software-defined drug dosage limit, pump manufacturers might specify certain maximum and minimum dosages for certain disorders by pre-programming their own infusion pumps with the drug dosage limitations.
In order to lessen or prevent inadvertent infused drug overdoses or underdoses, implanted drug infusion pumps require limits to be placed upon the drug delivery amount and/or frequency by health care professionals. An internal limit on the amount by which a patient can self-dose a drug, would be an improvement over the prior art implantable infusion pumps. Similar limits might prevent health care providers from inadvertently overdosing, or even underdosing treatments.